Currently, there is a range of methods for milk heating and milk frothing in coffee, espresso and cappuccino appliances, wherein steam is generated and supplied to the milk. The present invention will be explained and described in the context of these appliances, which does not alter the fact that the present invention also relates to other types of beverage makers, wherein the fluid beverage ingredient to be conveyed by the duct system of the beverage maker does not necessarily need to be milk.
According to a frequently used method, steam is used for both the purpose of heating milk and the purpose of pumping the milk out of a package or reservoir. In particular, the duct system may be connected to both a steam generator and the milk package or reservoir, wherein a geometry of the duct system may be such that the milk is drawn out of the package or reservoir under the influence of a flow of steam. A problem associated with the known beverage maker is that it is bothersome and time-consuming to clean the duct system after use. Especially a hose or tube for connecting the duct system to the milk package or reservoir is difficult to clean.
Over time, various solutions to the above-mentioned problem have been proposed. For example, disposable milk containers and disposable cartridges having a duct system for pumping, heating and frothing the milk may be applied, wherein there is no longer a need for cleaning, as used containers and cartridges may simply be thrown away and replaced by fresh containers and cartridges. However, the use of disposables is disadvantageous, as it involves relatively high costs and a relatively high environmental impact.
U.S. Pat. No. 5,611,262 discloses a cappuccino maker which has a milk receptacle and a base for the milk receptacle. The base has a lip extending upward from its edges to form a reservoir. When the milk receptacle is disengaged from the base, the cappuccino maker can be cleaned by pouring water or another cleaning fluid into the reservoir and activating the cappuccino maker. In this way, a milk frothing apparatus of the cappuccino maker is flushed of undesirable residue or buildup, wherein there is no need to empty the milk receptacle.
U.S. Pat. No. 4,960,042 discloses a device for frothing and heating milk for beverages. For the purpose of cleaning the device, the device is dismantled, wherein parts in contact with the milk and subject to incrustation by the formation of froth deposits are unscrewed from their locations, so that these parts can be placed in dishwashers or similar machines.
WO 2005/063093 discloses a device for preparing a heated liquid for use with a beverage making appliance. Skimmed milk is disclosed as an example of the liquid. The device comprises a liquid transport channel in communication with a liquid reservoir which discharges into a first chamber, said first chamber comprising a steam inlet which is connectable to a steam generator, and a second chamber which is connected to the first chamber via a restriction and which has a liquid outlet. In one embodiment, the liquid reservoir is a refillable reservoir. In that case, the liquid reservoir is provided in an element which is moveable between a first position in which it covers the liquid transport channel, the first chamber, the steam inlet, the restriction, the second chamber, and the liquid outlet during operation, and a second position in which it leaves these components exposed for cleaning purposes in a non-operating status.